Re: [R] Converting a data frame to matrix

From: Jim Lemon <jim_at_bitwrit.com.au>
Date: Fri, 28 Mar 2008 20:18:20 +1100

Adrian Johnson wrote:
> Hello:
>
> I have a tab delim file with 100 rows and 100 columns.
>
> I have numerical values in this table. What I want is to create an image
> color map with color gradation.
>
> my values range from -5 to 0. max value is 0.
>
> to acheive this, I need to convert my data.frame into matrix.
>
> I tried following :
>
> mydf <- read.table('mytable',sep='\t',header=T)
> mydf1 <- mydf[,2:100]
> colnames(mydf1) <- as.character(mydf[,1])

>
> here comes the trouble:
>
> mymat <- as.matrix(mydf1)
>
> -- numerical values become character values. -1 becomes "-1"

>
> mymat <- data.matrix(mydf1)
>
> -- whole matrix is filled with 1,2 and 3.
>

> Is there any other way I can do this.
>
> say row names are city schools
> colnames are student names
>
Hi Adrian,
Have you looked at color2d.matplot in the plotrix package?

Jim



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